Terminal board connection



Nov. 8, 1960 J. R. BARR TERMINAL BOARD CONNECTION Filed May 1, 1957 fifi/617751 cfa/7765 R. Barr, MR-7M United States Patent TERMINAL BOARD CONNECTION James R. Barr, Rome, Ga., assignor to General Electric Company, a corporation of New York Filed May 1, 1957, Ser. No. 656,393

1 Claim. (Cl. 339-268) 'Ilhis invention relates to an improved electrical connector, and more in particular to an electrical connector for facilitating the connection between a cable and a terminal on a terminal board. It will be obvious, however, that the connector of my invention may be advantageously employed for other purposes, such as the joining of two electrical cables.

Many cases arise where it is desirable to connect a plurality of electrical cables to terminal studs closely disposed on the surface of a terminal board. The closeness of the terminals, while possibly electrically undesirable, is frequently mandatory in order that the space occupied by electrical apparatus to which the terminal board is connected is not excessive.

In practice, the terminal board is frequently comprised of an insulating panel bolted to electrical apparatus. A plurality of terminal studs are assembled in apertures in the insulating panel, and seals may be provided to prevent the passage of fluid through the apertures in the panel. In order to connect cables to the terminal board, it has previously been the practice to employ cable terminals having a sleeve portion aiiixed to ythe end of the cable and a flat portion having a transverse opening adapted to be slipped over the terminal stud. A selflocking nut is then employed to hold the cable terminal on the terminal stud. It is frequently desirable, and a necessity when the terminal board has close spaced terminals and is employed on high voltage apparatus, to arrange the cables so that they approach the terminal board transversely of the plane of the insulating panel. In this event, it is necessary that the flat portion of the cable terminal lie in a plane transverse to the axis of the cable, thereby displacing the axis of the terminal stud from the axis of the cable. In this case the cable terminals provided have a right angle bend.

Since the terminal studs are frequently nested as closely as possible to keep the supporting panel as small as practical, the displacement between the axis and the terminal stud and the cables shortens the metal-to-metal distance between parts, and consequently reduces the electrical breakdown strength of the assembly. As long as the right angle bend in each cable terminal retains its original shape and the oifset or displacement of adjacent cable terminals are not positioned toward one another, the difliculty of maintaining adequate insulation is reduced. The cables, however, are frequently assembled in very restricted quarters, and it is therefore difficult to avoid occasional bending or distorting of the cable terminals. Furthermore, it is difficult to always be-sure that the offset position of one cable terminal is well away from the offset positions of adjacent cable terminals, or adjacent terminals.

It is therefore an object of this invention to provide all improved electrical connector.

It is a further object of this invention to provide a cable connector for connecting a cable to a terminal board, the connector being characterized by the minimizing of danger of reduction of electrical strength of the assembly resulting from misalignment of cable terminals.

A still further object is to provide an improved terminal board connector `for connecting a cable to a terminal board having a plurality of closely nested terminal studs, the connector having coaxial alignment between the terminal studs and connecting cable to minimize the danger of reduction of electrical strength.

Still another object of this invention is to provide an electrical connector for connecting a cable to a terminal board, the connector providing a mechanical advantage to facilitate the establishing of good electr-ical contact between the terminal stud and a cable.

Briey stated, in accordance with one aspect of my invention, I provide a first threaded terminal means,

which may be a terminal stud disposed on a terminal board. I also provide a second threaded terminal means which may be a cable terminal affixed to the end of a cable. The iirst and second terminal means are coaxially disposed, and the end of the second terminal means may abut the end of the first terminal means, although this is not necessary. A threaded conductor means is provided having a rst threaded portion adapted to be connected to the threads of the lirst terminal means and a second threaded portion adapted to be connected to the threads of the second terminal means, the connector means being provided to join the irst and second terminal means. The threads of the rst and second portions of the connector have different pitches and advance in the same direction, (i.e., both threads are right-hand threads or both are left-hand threads).

While the specication concludes which the claim particularly pointing out and distinctly claiming the subject matter which I regard as my invention, it is believed that the invention will be better understood from the following description taken in connection with the accompanying drawings.

In the drawings:

Fig. 1 is a cross-sectional assembled view of one form of the electrical connector of my invention, and illustrating the connector joining a cable to a terminal board,

Fig. 2 isa partial disassembled View of the connector of Fig. l,

Fig. H3 is a cross-sectional view of another form of the connector of my invention,

Fig. 4 is a partially disassembled view of the electrical connector of Fig. 3.

Referring now to the drawings, and more particularly to Fig. 1, therein is illustrated a threaded terminal stud 10 extending from a terminal panel 11. A ceramic insulating member 12 may be provided on the terminal stud toincrease electrical sparkover distance. A cable terminal 13 is provided electrically and mechanically connected to the end of an insulated cable 14. The cable terminal 13 may be atxed to the cable 14 in any conventional manner, such as by providing an enlarged sleeve portion 15 on the cable terminal, the sleeve portion 15 extending over the end of the cable 14 and being crimped or soldered thereto. The cable terminal 13 also has an externally threaded portion 16 extending coaxially from the end of the cable 14. A conducting sleeve connector 17 is provided for joining the terminal stud 10 and the cable terminal 13. One end 18 of the sleeve connector is threaded over the end of the terminal stud 10, and the other end 19 of the sleeve connector is threaded over the threaded end of the cable terminal 13. The central portion of the sleeve connector 17 has a relieved portion 20 free of threads. The end 21 of the extending portion of the cable terminal 13 may also be removed of threads, and

it will also be desirable in this form of my invention to relieve the central portion 22 of the cable terminal 13 between the threaded portion 16 and the sleeve'portion 15. The threads of the terminal stud have the same diameter and advance in the same direction as the threads of the threaded portion 16 of the cable terminal, but the pitch of the threads of these two members is different, as will be explained in more detail in the following paragraphs.

Referring now to Fig. 3, the electrical connector therein illustrated has a terminal stud 30, cable terminal 31, and sleeve connector 32 as in the terminal connector of Fig. 1. 'In the embodiment of my invention illustrated in Fig. 3, however, while the threads of the terminal stud 30 and cable terminal 31 advance in the same direction, the threads have a different diameter as well as a different pitch. The connector 32 is internally threaded on one end to receive the threads of the terminal stud 30 and is internally threaded on the other end to receive the larger diameter different pitch threads of the cable ter minal 31.

In the connector of Fig. 3, it is noted that neither the central portion of the connector 32 nor the end of the cable terminal 31 are relieved. In this -arrangement it is not necessary to provide a removed portion on the cable terminal 31 between the threaded portion and sleeve portion. It may be desirable, however, to provide a relieved portion 33 on the terminal stud, the relieved portion being disposed between the threaded end and the ceramic bushing.

To assemble the connector of my invention, the sleeve is first threaded onto the end of the member having the smaller pitch threads. Thus, in assembling the connector of Fig. l, the sleeve 17 is threaded onto the end of cable terminal 13, as shown in Fig. 2. Then, the sleeve is aligned against the end of the terminal stud 10 and threaded onto the terminal stud. Since the pitch of the threads on the terminal stud is greater than the pitch of the threads on the cable terminal, the sleeve advances on the terminal stud faster than it leaves the threads of the cable terminal. Thus, the gap between the terminal stud and cable terminal gradually closes until the end of the cable terminal is forced against the end of the terminal stud. Since one turn of the sleeve closes the gap a distance equal to the difference in the pitch of the threads of the terminal stud and cable terminal, the arrangement provides a mechanical advantage such that a moderate torque applied to the sleeve results in a large force between thc ends of the terminal stud and cable terminals, thereby ensuring positive electrical contact. The difference in thread pitch of the members has Yalso been found to provide the advantage that the connector is selflocking.

As illustrated in Fig. 2, before being threaded on the terminal stud, the sleeve is threaded completely on the cable terminal so that it extends beyond the threaded portion. This enables the sleeve to fully engage the threads of the cable terminal when the sleeve is threaded on the terminal stud. The central portion 20 of the sleeve and end 21 of the cable terminal are relieved to avoid jamming of the sleeve threads of one pitch with threads 4 of the terminalstud or cable terminal having a different pitch.

The assembly of the arrangement of Fig. 3 is the same as that of Fig. 1, with the sleeve being threaded first on the member having the smallest pitch threads. In this instance, the sleeve is threaded first on the terminal stud 30 (Fig. 4). Since the portion of the sleeve 32 having larger pitch also has a larger internal diameter, there is no danger of interference of the threads of different pitch, and it is thereby not necessary to relieve either the central portion of the sleeve or the end of the terminal stud. This permits a reduction in the axial length of the connector assembly.

It will be understood, of course, that, while the forms of the invention herein shown and described constitute preferred embodiments of the invention, it is not intended herein to illustrate all of the equivalent forms or ramications thereof. It will also be understood that the words employed are words of description rather than of limitation, and that various changes may be made Without departing from the spirit or scope of the invention herein disclosed, and it is aimed in the appended claim to cover all such changes as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

An electrical connector comprising a rst externally threaded terminal means, a second externally threaded terminal means, and an internally threaded sleeve con' nector means for joining said first and second terminal means, the threads of said second terminal means being larger in both diameter and pitch than those of said first terminal means, said first and second terminal means being coaxially disposed, said sleeve means having one end threaded to receive said first terminal means and a larger end threaded to receive said second terminal means, the inner diameter of said larger end being greater than the outer diameter of said first terminal means, the threads of said first and second terminal means advancing in the same direction, said sleeve means thus being adapted lto be threaded on to said first terminal means with said first terminal means extending into said larger end of said sleeve, rotation of said sleeve means causing said second terminal means to axially advance into contact with said yfirst terminal means whereby the axial distance traveled by said second terminal means before making contact with said first terminal means is 

